After having the TI steering trouble since day 1, and seeing the post on describing how the rudder does not seat in the groove properly, I checked mine on land and it appeared to be trouble free. However, my rudder always seemed to work except when at higher speeds. I surmised that no matter how tightly the rudder line was pulled, the rudder is still able to pop out of the groove when the water pressure builds, causing the lack of steering (maybe you saw my video on a previous post).

My new theory (after 4 days of sailing this past week) is that the rudder just isn't big enough to turn the boat. This past week I was sailing in 15-20 mph winds in 3-4 foot chop. Every time I had the boat slightly into the wind so that I was running at a good speed, the boat refused to turn away from the wind. This would happen when I was sailing with the wind coming towards either side of the boat. However, if I trimmed the sail out, effectively slowing the boat, the boat would then begin to turn away from the wind. This would happen when turning either to starboard or port, so I assume it's not the rudder popping out of the groove issue. If any of you master sailors have any other input on the physics of why this would happen I'd love to hear it. That withstanding, I believe when the boat is moving at a fast pace the rudder does not have enough surface area to turn the boat from running slightly into the wind through perpendicular, and ultimately away from the wind.

Now, onto the very frightening good stuff...the evidence. I have spend a lot of time holding the rudder to one side or the other while sailing with no direction change in the boat. This week the rudder completely failed. I tried to use a paddle to steer myself back while sailing. This is when I realized the tremendous amount of pressure that is exerted on the rudder. After feeling this force for way too long I began to wonder how the rudder is able to handle this force when it is turned flat against the oncoming water, especially when it is turned flat against the water and the boat continues to go in a straight line for lengthy periods of time. You would think the rudder would just rip away from the boat. Well this is exactly what happened. I'll spare you the frustrations, the danger of my situation, and my fear to now take this boat out on any expedition trip. When the rudder first went limp I assumed I had a broken rudder pin. But when I finally made it back to shore I noticed that was not the case. The rudder had actually been pulled away from the boat. See photo:

I could not believe my own eyes, but the lower screw had completely been ripped apart!

Here's another view:

and the top screw was obviously bent:

After feeling the force the water exerted on the paddle, and knowing how long I've spent holding the rudder to one side or the other with nothing happening other than the boat continuing to move briskly in a straight line, I can begin to understand how this single screw could fail. Nonetheless, it was very shocking that this could happen to a stainless steel screw and nothing else breaks in the assembly. I believe the rudder would have to be turned sideways and locked in the down position for some time, while the boat continues to move forward in a straight line, for this screw to fatigue and fail like this. This is why I have deduced that the rudder just isn't big enough to turn the boat when moving on the course I described at speed.

I have replaced the screws and the only ill effects left are very sloppy rudder handles. There's probably 3 inches of play in the handles now before the rudder moves. I have not spent much time trying to determine a fix for this, but if anyone has had this problem and knows how to tighten this movement, I'd appreciate the input. I'm thinking that maybe some of the knots slipped in the steering lines and need tightening, but this does not seem likely. Of course, a stainless steel screw being snapped without any plastic hardware failing first also seems unlikely.

A part of your original the problem, at higher speed, you need to slowly release the sheet line as you turn away from the wind. The sail angle actually steers the boat as much, if not more than the rudder at speed.

It sounds like a case of the sail overpowering the rudder. It doesn't improve the boats performance to keep the sail too tight while trying to force the rudder to respond. The rudder is acting like a brake when it is deviated, so it's like trying to brake a car while keeping your foot on the accelerator. The boat's reluctance to turn away from the wind is called weather helm and it exists to some degree in most sailboats, particularly those without a foresail. As you discovered, the remedy is to depower the sail a bit, either by easing the mainsheet or furling. That's one reason why the boat often goes faster with the sail partly furled - it doesn't have to fight against the rudder to maintain a straight course.Someone (Kayaking Bob I think) advised me early on to practice steering with the sail only and it was excellent advice.

I have spend a lot of time holding the rudder to one side or the other while sailing with no direction change in the boat.

That's pretty weird! How can you be sailing 'straight' with rudder fully over?

It's called stalling the rudder. I do it, too. The way to get out of it is to either play out the sail to release the side load on the rudder, or to let the bow come up into the wind until the rudder begins to respond.

Thanks to all the knowledgeable replies, this novice now has a better understanding of more of the physics behind sailing so my time spent on the water will be more enjoyable. I looked up "weather helm" and found some additional very informative articles, if anyone is interested, such as this wiki:http://en.wikipedia.org/wiki/Weather_helmThis one has a good diagram explaining the phenomenon:http://www.sailingusa.info/sailboat_balance.htm

Back to the product failure, hopefully, Hobie will recognize this and add an additional screw towards the bottom of the assembly, or somehow modify the design to help eliminate this type of failure, due to such a massive moment of inertia, in the future.

Of course, a stainless steel screw being snapped without any plastic hardware failing first also seems unlikely.

Yes, it is very unlikely. After closer inspection, I've noticed the twist and stow mechanism is cracked. That's probably why I have so much play in the rudder handle. Plus, the rudder will not flip down with input from the down line anymore. You can actually see the crack a bit in the first picture I posted before I realized it. I guess I was so amazed at the screw shearing, I couldn't see past that. Here's another photo with a better view of the crack.

Well that certainly shouldn't have happened with normal usage. Could it be that the rudder pin on the TI is TOO strong? Is this covered by warranty?

I know it seems improbable this could happen with only water pressure. After using the paddle as a rudder I now know the stress the rudder must endure is pretty high. This happened on day 2 of my week long vacation this past week. All sailing was done entering through the shore break into deep water. It happened after I had been out for about an hour. I was probably close to 1/2 mile offshore and in 20-30 deep water when it occurred. This week, or on any previous trips I have never run aground with the rudder. Nor have I ever had cause for concern that it was damaged during transport. I'm very careful with the boat except for when I'm trying to see just how overpowered I can sail it. Most of my steering due to "weather helm" was me trying to steer to starboard. The location of the crack makes sense if the rudder was positioned so the starboard side of the rudder was facing the oncoming water. The plastic and metal must have just fatigued from several sessions when it finally decided to fail. What scares me is this was only the 6th time I had been out on the boat. Probably 4 of those times I experienced weather helm quite a bit. So it did not take much for this to happen which is scary. Maybe the rudder pin IS too strong as that should be the weak point. I know I was complaining about the rudder not being big enough to steer out of the weather helm, but on the other hand, maybe the new larger rudder is too big for the twist and stow system due to the extra forces it must endure.

Scary stuff losing your rudder control . I had a simular experience this weekend when the rudder wouldn't respond I realized the rudder was dragging loose seaweed so I lift it up and lower it back and everything was back to normal , I had to do it a few times, this time of the year the seaweed died and float on the surface all over the bay.